1. Field of the Invention
The present invention relates to gelatinous cushions comprising a gelatinous material enclosed at least partially in a thin protective membrane.
These cushions have various applications in the field of comfortable wear. In particular, the patent applications FR 2 326 717, WO 85/05700 CH 656234 and US 2 032 843 have already proposed the mounting of such cushions on a spectacle or eyeglass frame in the areas where the frame irritates and hurts the epidermis, especially on the arms of the frame cr in the nasal support areas.
Furthermore, cushions of this kind can also be supplied in the industrial field, for example as vibration dampers.
The present invention is aimed at improving the performance characteristics of these gelatinous cushions as regards comfortable wear or the damping of shocks and vibrations.
2. Description of the Prior Art
FIGS. 1A, 1B and 1C give an exemplary view of a prior art nose pad 1 having the structure of a gelatinous cushion. The nose pad 1 has a thin elastic membrane 2 whose periphery is soldered or bonded to a rigid or semi-rigid pad-shaped support 3 made of plastic material. The membrane 2 forms a tightly sealed cavity with the support 3. A gelatinous material 4 is trapped in this cavity. The support 3 has a protrusion 5 on its other face in which a hole 6 is made enabling the mounting and hinging of the nose pad on an eyeglass frame.
The theoretical advantage of a nose pad 1 of this kind is that, under the effect of crushing, especially when the pad 1 is resting on the nose, the gelatinous material 4 absorbs the crushing force, dampens the shocks and provides an excellent degree of comfort.
However, a closer look at the "behavior" of the nose pad 1 when it is subjected to crushing, for example when it is crushed with the finger as shown in FIG. 1B, shows that, as and when the pressure on the pad is accentuated, the gelatinous effect gradually disappears and is replaced by an elastic effect due to the stretching of the membrane 2. This stretching is prompted by the compression of the gelatinous material 4 trapped in the membrane 2. This elastic stretching effect shall be called the "membrane effect". Thus, when the nose pad 1 is resting on the nose, as shown in FIG. 1C, the crushing produced by the weight of the frame is such that the membrane effect is predominant over the gelatinous effect.
In short, a prior art gelatinous cushion subjected to fairly heavy crushing displays a certain degree of hardness and does not provide wearing comfort greater than that of a cushion filled with a fluid or a gas, the membrane affect being predominant. This drawback has not been discovered in the prior art. This explains why, in the above-mentioned patents, it is proposed to fill the cushions with a gel, fluid, or gas without any distinction being made between these materials.